Grinding machine



Sept. 1s, 1928.

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R. A. HEALD ET AL GRINDING MACHINE Original Filed May 1l, 1926 l0SheetS-Sheet 7 @WMV 1%/ Sept. 18, 1928. 1,684,487

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GRINDING MACHINE Original Filed May ll, 1926 l0 Sheets-Sheet 8 Sept. 18,w28. 1,684,487l

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v GRINDING MACHINE original Filed May 11, 192e 10 sheets-Sheet. 1o

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Ccxre I H hbe EM@ mi@ amm Patente-d Sept. 18, 1928.

UNITED STATES y 1,684,487 PATENT oFFIcE..

RICHARD A. HEALD, CARLE J. IIIGHBERG, AND EDWARD M. TAYLOR, OFWORCESTER, MASSACHUSETTS, ASSIGNORS TO THE HEALD MACHINE COMPANY, OFWORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

GRINDING MACHINE.

Application led May 11, 1926, S'erial No. 108,379. Renewed April 3,1928.

The invention relates, to grinding machines, particularly those adaptedto grind the internal peripheral surfaces of sleeves, gears, bushings,and like articles. The embodiment of the invention described herein andillustrated in the accompanying drawings, is an improvement upon and anaddi tion to the prior invention shown and claimed in the copendingapplication of Kempton and Gallimore, Serial No. 6,689, filed February4, 1925, and to the prior invention shown and claimed in the copendingapplication of Heald, Guild, Burns and Garne, Serial No. 4,466,filedJanuary 24, 1925, and also to the prior invention shown and claimedin the .copending application of Heald and Guild, Serial No. 25,900,filed April 25, 1925. The first two of said inventions provide acalipering mechanism having a member in contact mechanism controlledthereby for automatically dressing and-truing the grinding wheel at agiven stage in the reduction of a workpiece, and further mechanism forautomatically separating the grinding wheel and workpiece when thelatter has reached the finished size. It is to be understood, however,that the mechanism of the present invention can equally well be appliedand added to the invention shown and claimed in the copendingapplication Serial No. 48,734 of Waldo J. Guild, filed August 7,1925,'which shows controlling means for similarly dressing the grindingwheel and causing final separation between wheel and workpiece, saidcontrolling means deriving its movement from the transverse feedingmechanism which feeds the grinding wheel relative to the workpiece in alateral direction to take successively deeper cuts.

The present invention provides means for' automatically dressing therapidly rotating grinding wheel a plurality of times durin ythe grindingof a workpiece, said severa e5 dressing operations being achieved bymovn ing into the path of the grinding wheel a plurality ofdiierenttruing devices, desirn ably diamonds. To that end, in thepresent illustrative embodiment of the invention, these several truingdevices are mounted on different members which are movable into anddatei thepath of said grinding wheel, and thus the latter is trued atdistinctly different sta frcs in the grinding oiga given workpiece. Itis within the contemplation of the invention, however, that a givendressing devlce might be made to assume two different operativepositions, and thus it will be' seen that ,the present' inventioncontemplates, broadly, the automatic dressing of a grinding wh-eel atdistinctly dierent positions of said wheel in its transverse movementin'cutting relation to a workpiece.

lhe purpose for the above is to keep the grm'dmg. wheel sharp and freecutting and true 1n shape at all stages in the grinding of a workpiece,thus greatly increasing the accuracy of these machines over what wasposslble by the prior art. ther and further objects of the inventionywill appear from the following detailed description taken in connectlonwith the accompanying drawings, in

which-` 20 with the internal surface of a workpiece, and

Fig. 1 is a front elevation of a grinding machine built in accordancewith the invention.

F 1g. 2 1s a planview of the work calipering mechanism and Contact box.

F ig. 2'i is a fragmentary sectional view on the line -a of Fig. 2

Fig. 3 is a sectional view on the line 3-3 of Fig. 2.

- 4 is a wiring diagram of the machine.

Fig. 5 isa front elevation of certain progressive control mechanismcontrolling the different dressinvf operations, the cover of the box 1nwhich t esame is contained being removed.

Fig. 6 is a side view, partly in section and partly in elevation of themechanism shown 1n Fig. 5, together with certain hydraulic valves. v

Fig. 7 is a sectional view on the line 7--7 of Fig. 6.

Fig. 8 is a diagram of the prcssure Huid connections between theaforesaid hydraulic valves and the dresser moving mechanism.

Fig. 9 is a horizontal sectional view showing the movable dressers andtheiumountings.

Fig. l0 is a detail view of a certain control device.

Fig. li is a. rear elevation of the dresserl moving ieciganisms andcertain speed conview partly `in section and L ration et the mechanismof 1g. 11, the being taken on thev line 12--12. i

Fig. 13 is a sectional view on the line 13-13 of Fig. 11, and

Fig. 14 is a sectional view on the line 14-14 of Fig. 12.

Fig. 15.is a perspective view of the table dogs and associated mechanismin the position which they occupy when the grinding Wheel is operatingupon the'workpiece.

Like reference characters refer to like parts throughout the drawings. y

Referring first to Fig. 1, the machine provides the usual reciprocatorytable or carriage 1 which is ordinarily provided in any internalgrinding machine. In such a ma'- chine, either the grinding wheel or thework to be ground may be carried on the table 1, the reciprocation ofthe latter being utilized in either case to produce a relativetraversing movement between the grinding wheel and the work. As hereshown', the table 1 supports and carries a wheel head 2, while the workwhich is to be operated upon is heldl in a work head 3, the latter beingcarried by a bridge 4, which spans the slideways provided by a machineframe for the back and y forth lnovement of the table 1.

This back and forth movement of the table 1 to cause the rotatinggrinding wheel 5 to make the required interior traverse of the rotatingworkpiece 6 may be'imparted in any well known manner, as for instance,bythe use ofthe fluid pressure controlling and reversing mechanism whichforms the subject matter of United States Patent No. 1,582,468,

= vto Heald and Guild, granted April 27, 1926.

Except in connection with the slowr down valve hereinafter described,such mechanism, or its equivalent, forms no part of the presentinventiomand a detailed description thereof is therefore unnecessary; itis sufficient to note for the purposes of the present application, thatthe driving means employed for the reciprocation of the table V1, be ithydraulic drive, or gear drive, or any other type, procures the reversalof said table at each end of thev latters normal working stroke by theuse of spaced adjustable dogs 7 and 8, carried by the table 1 andadapted to alternately engage and move a reversing member 9; the latter,during the grinding operation, when the wheel 5 is. moving vback andforth within the workpiece 6, is situated between the two dogs 7 and 8-in position to be struck alternately by ysaid dogs, and by itsconsequent movement, first in one way and then the other, effectsthereversals in the travel of table 1. In the machine hereinillustrated, the grinding wheel 5 is rotated at high s` eed in anysuitable manner, as for instance, y a belt drive for the wheel spindle10, the latter for this purpose carrying a pulley 10. The workpiece 6visalso rotated, but at awslower speed, this rotation being imparted in anysuitable manner as by a belt drive, not shown, from a countershaft.

The machine also embodies the usual instrumentalities for both manualand automatic cross feed between work and. wheel,

here shown as embodied in a screw shaft 11 for feeding the wheel -head 2transverse of each reciprocation of the table 1, by a fixed dog or stop12 which is engaged by a roller 13 on the end of a pivoted arm 14; themovements of said arm are transmitted through a pawl 14l and ratchetwheel 14b to the screw shaft 11, thereby to obtain the automatic crossfeed of the grinding wheel 5 at each reciprocation of the table'.

As shown in Figs. 2 and 3, a member 15 has at one end a work caliperingpoint 16 adapted, during vthe operation of grinding a workpiece, to bearagainst the internal surface which is being ground, and to maintain itscontact with said surface as the hole in the workpiece is graduallyenlarged by the grinding action of the wheel. The member 15 is to allintents and purposes a lever, said member, for the movement required ofit to maintain the point 16'in constant Contact with the interior of thegradually enlarging hole in the workpiece, being supported by a pair offlexible U-shaped flat springs 17 and 18,which springs cross each other,`and are attached to two adjacent sides of a rectangular block portion19 of member 15. At their other ends the crossed springs 17 and 18 areattached to two inner surfaces 20 and 21 of a box 22, (which in Fig. 1is shownturned away from its calipering position) thesesurfaces 20 and21 being at right angles to each other, and the box 22` providing anopening 23 of suicient size to permit the inward extension 15, of member15 to move freely aboutthe vpivotal axis which is afforded by theintersection of the planes of the U-shaped springs 17 and 18. Thispivotal movement is accomplished by the flexing of these two springs,and takes place in the entire absence of lost motion since there is nobearing or pivot pin. Consequently, any'movement of the extension 15* ofmember 15 within the box 22, is invariably in exact accordance with themovement of calipering point 16 in maintaining contact with the surfaceof the graduallyenlarging hole in the workpiece.

- Suchmotion of the member 15 is adapted' draws the parts together andmaintains the i end of a screw 28 carried by the lever 24 in Contactwith the extension 15, said ,screw being adjustably threaded in lever 24and passing at its head end through a suitably enlarged slot or hole 29in box 22, so as to permit adjustment from the exterior of said box. Byturning the screws 28, the indicator lever 24 can belmade to assume anydesired position relative to the member 15, and said screw 28 ismaintained in any given setting, and displacement-thereof prevented byany suitable friction device, such as a bindingl screw 30. vWith thearrangement above described, a very slight movement of the caliperingpoint 16 is multiplied many times in being transmitted to the indicatorlever 24, as will be readily understood.

In the operation of the mechanism, the calipering point 16 maintainscontact with the work, the movement of member 15 for, this purpose beingobtained by the pressure of a sprlng 31, and such movement, greatlymultiplied, being transmitted through the above described connections tothe indicator lever 24.

The extension 15a carries a loose piston 32 located in an oil cylinder33, which arrangef ment dampens any vibrations which may be imparted tothe member 15 in case the workpiece, at the commencement of the grindingoperation, is badly out of round. Such dampening means increases theeiiiciency of the indicating and circuit making mechanism, as vibrationslare apt to cause premature making of the circuits,hereinafter to bedescribed.

The multiplied movement of lever 24 -is made use ofuutyntlin operationrthe wheel dressing iristrumentalities a plurality of times, and finallyto bring about a cessation of the grinding to cause the grinding wheel 5to withdraw from-the workpiece 6. To this end the lever 24 carries aplurality of contact terminals, in this embodiment shown as four, .allof which are unins'ulated from, the lever 24, which is groundedinto themachine frame through its ivot 25; The terminaLnumbered 34 is a apted tobring about the cessation of the grinding operation. The otherterminals, namely 35, 36 and 37, are adapted to ybring about the severalstages of dressing, and as will hereinafter appear, it is possible tocause the grinding wheel to be dressed and trued a greater number oftimes than the number ofdistinct and different dressing diamonds. Thatis to say, the mechanism can be. arranged to cause the grinding wheel tobe .dressed a plurality of tlmes. by one of the several dressingldiamonds and but a single time on the others, or it can be arrangedto'cause the wheel to be dressed a plurality of times by each. Asillustrated, however, there are but three terminals controlling thedressing opera-tions, and just two"i dresser moving devices are shown,so necessarily the grinding wheel is dressed twice by one diamond andonce by the other.

nals 36 and 37, which subsequently make con? tact in the order named,cause the grinding wheel to be dressed by the other dressing device. Inthe paths of the contact terminals 34, 35, 36 and 37, the box 22provides insulated stationary terminal contacts 38,' 39, 40 and 41. As aove indicated, the movement of lever 24 causes terminals 35 and 39 tocome into contact first; subsequently terminals 36 and 40, 37 and 41,and finally terminals 34 and 38 come into Contact. In order to permitthis succession o f contacts, the moving terminals 35, 36 and 37 arecarri-ed by flat springs 42, which normally pressagainst rigid members43, so that the said terminals have a fixed position of rest `relativeto the indicating lever 24, but-can be readily displaced therefroml inone direction. Thisv construction is clearly shown in Fig. 2a, which,while a sectional View of terminal 37, shows equally well theyconstruction ofthe other two flexible terminals 35 and 36. v

Asclearly described in the aforesaid application of I-Ieald,y Guild,Burns & Garno, the box 22 is carried by a bracket 44 which provides apivotal mounting for it, and when t-he yfinal withdrawal movement oftable 1 takes place, withdrawing the wheel 5 from the workpiece 6, a cammember, not shown herein, engages a lever or a roller at ,the endthereof and swings the box 22 carrying the calipering lever k15 awayfrom the workpiece. A spring 45, see Fig. 1, automatically returns thebox 22 to its operative position as the wheel 5 enters a subsequentworkpiece 6,-and means is provided to allow the calipering point 16,generally a diamond, to enter the new workpiece without striking themouth of the latter and chipping the point 16. 'It is not believednecessary to describe thismechanism and t-he various adiustments indetail, as they have nothing to do with the present invention, andenough of the calipering mechanism has been described to illustrate saidpresent invention.

Referring now toFig. 4, the instrumentalities whereby a plurality ofwheel dressing operations may be automatically inaugurated will now bedescribed. `The character G in`- dicates a generator ot' any desiredsort, preferably supplying direct current. One terminal ofj saidgenerator is grounded and the lll),

other terminal is connected by means of a branching lead`46 to the coilsof two electromagnets 47 and 48. The other end of the coil v of'electromagnet48 fis connected by a lead 49 to the stationary'terminal38. The other end 'ofthe coil of elcctromagnet 47 is connected by a leadv50 to af. stationary terminal plate 51 of a switch, `generallydesignated by the nuf meral 52.

The stationary terminals v39, 40 Y and 41 are connected,v respectively,leadsale!)' and into the path of a dressing diamond.

rThe instrumentalities whereby this action is brought about willpresently be described. Also the magnet 47 actuates a'certain hydraulicvalve to move one of the dressing diamonds into the wheel truingposition, which one of the several dressing diamonds is moved, beingdetermined, as will appear, by the position of the moving parts ofswitch mechanism 52. The magnet 48, when energized, brings about acessation of the grinding, and prepares the machine for. theintroduction of va new workpiece.

The mechanism whereby the energization of magnet 47 causes thereciprocatory travel or stroke of table 1 to be amplified, is as follows-As shown in Fig. 1, the left hand table dog 8, which limits therighthand movement of table 1, is carried by a'block 59, which instead ofbeing secured directly to the table 1, as is the case with the block'60of do 7, is mounted so as to be capable of sliding reely longitudinallyof said table. Under normal conditions, Whenthe table is making itsusual working reciprocations to traverse the grinding wheel 5 backandforth within the work# piece, the block 59l of dog 8 is held indefinite spaced relation to a block 61, which latter, the

same as the block of right hand dog 7, is a stationary block adapted tomaintain itsA predetermined setting or adjustment longitudinally of thetable 1, as given it by any suitable adjustment of adjusting and holdingdevices, such for instance, as the hand screw nuts 62, 62' applied toboth blocks 6() and 61 and engaging with the screw rack 63 on the table1.

The device employed to hold the slidable block 59 in spaced relation tothe fixed block 61 is here shown as alatch lever 64 pivoted at 65 onblock 61, and having its free end disposed by gravity in abuttitnrelation to a shoulder 66. on block 59, there y holding the block 59 `ata predetermined distance to the right of block 61. When the latch member64 is lifted, as hereinafter described, to free its end from theshoulder 66, the normal connection between the slidable block 59 andthefixed block 61 is broken, and when this occurs on the right handmovement of table 1, the dog 8 will bear without effect against themember 9. Thus the right hand movement dressing devices, one ,of which,as will'be de-v of the table 1 on' this particular stroke will beextended beyond the usual reciprocatotry workingpath, and the grindingwheel 5 will be carried out of the holein the workpiece to a point justbeyondthat occupied byfthe scribed, has .been moved into operativeposition as the amplified right hand travel of table 1 begins.lThisamplified right hand travel of table 1 involves relative slidingmovement between said table and the block 59, owing to the obstruction.which the re-A thusafiorded for the block 59 enables the dog 8 to shiftthe member 9. This procures the reversal of the table 1, and the lefthand movement of said table thus inaugurated is caused to restore theparts automatically to normal position in the following manner.

A member 67 pivotally mounted on the frame of the machine has a pair 0finclined surfaces 68 and 69 for cooperation, respectively, with inclinedsurfaces 70 and 71 at the lower corners of the block 59. A spring 72presses said member 67 upwardly. In the normal grinding operation of themachine when the blocks 59 and 61 are connected by latch 64, thesurfaces 68 and 69, although in the pathof block 59, offer no effectiveobstruction to the back and forth travel of said block in unison withthe table 1, it being obvious that when either lower corner of the blockunder these conditions strikes either of the bevelled surfaces 7 0 or71, such contact will wedge the spring 72 downwardly, said springyyielding sufciently to allow the block 59 to pass Vover the member 67.However, when the block 59 has been freed from the block 61 as abovedescribed, to amplif a single -right hand stroke vof the table 1, t eensuing reversal of said table, with the block 5 9 still free, finds thesurface 68 in position "to contact with the corner 7 0 of said block,and under these conditions the obstruction offered is suflicient toovercome whateverlfriction there may be tendin to cause the block 59 tomove to the left wit the table. The block 59 being thus held stationarywhile the table 1 and block 61 continue to move to the left, thelatchmember 64'finally resumes its normal'position relative to the block59, the end of said latch member dropping behind the shoulder 66 and theparts being thus automatically restored to normal position at theconclusion of each single amplified reciprocation of the table 1. Duringnormal reciprocation of the table 1 a roller 75 is underneath the latchlever 64 and energization of the magnet 47 attracts an armature member 73,I to which is attached a lever arm 74 carrying said roller 7 5.Movement of this lever arm 74 is thus adapted to raise the latch lever64. The provision of the roller 75 is, of course, merely to reduce wear,and it may be dispensed with without detriment, Vespecially if the partsare hardened.

The ma in dotted ines in Fig. 1, being shown as inclosed in a box-likestructure 76 on the front ofthe machine frame. The magnet 48, kshown inthe wiring diagram of Fig. 4, is located directly behind the magnet 47,the same pivot 77 that serves to hold the armature 73 and lever arm 74serves also to hold an armature 78 and an arm 79 associated withelectromagnet 48. As heretofore stated, energization of magnet 48 isadapted to cause nal separation of work and wheel, and this is el'ectedin the-followin manner Attraction o? armature-78 lifts arm 79,interposing the free end of the latter in the path of table dog 8, whichdog, as heretofore pointed out, normally, on the right hand workingstroke` of the table, strikes and moves the reversing member 9 to causea reversal in direction of table travel. The dog 8 is pivotally mountedat 80 (see Fig. l) on the carrying block 59 and normally rests bygravity against a pin 81. When the arm 79, as above described, movesupwardly into the path of dog 8, the free end of said dog, on the righthand movement of the table, engages with and rides upon the upwardlyinclined surface of arm 79, and is thus carried clear of reversingmember 9. The table 1, therefore, continues its movement to the right,carrying the grinding wheel 5 out of the work and well past the dressingdevices,

being iinally brought to a stop by any suitable means, such, forexample, as disclosed inthe aforesaid patent to Heald and Guild,

' shaft 85 which is suitably journalled in the l Still referring to Fig.1, the block 61 has attached thereto a pair of switch operating do s 82and\83. These dogs are somewhat dierentin shape, and are in differentvertical planes. An arm 84 is fastened to a box structure 76 on thefront ofthe machine. A second arm 86 likewise fastened to shaft 85, hasa link 87 connected to it at its end. The arm 84 is in the path of dog82. A third arm 88 isloosely mounted on shaft 85, which serves as apivot for it, and this arm 88 is in the path of dog 83, whose bevellededgesare adapted to depress it. A link 89 is connected to the end of arm88.

With the table in the position of Fig. 1, which is the positionitautomatically assumes at the completion of the grinding on a givenworkpiece, the operator, after placing an unground workpiece in thechuck 6a, Grasps a lever 90 and moves it to the' left, which, byconnections, not shown, moves the reversing member 9 to the right andsets the table 1 in motion to carry the wheel 5 into the new workpiece.In so moving, the table 1 carries the dogs 82 and 83 past the arms 84and 88, first depressing the arm 88 and consequently also the link 89and subsequently rocking the arm 84, raising the link 87.

Refe ing now to Figs. 5 and 6, a sultable casing 1 is attached to thefront of the machine, below the box 76. Suitably journalled in thiscasing is a shaft 92. As shown in Fig. 6, a ycoil spring 93 surroundsthis shaft, one end of the springl being fastened to' a member 94fastened .on the end of shaft 92 and the other end being anchored in thecasing 91. At the forward end of shaft 92, see Fig. 5, an arm 95 ispivotally mounted. This arm carries a spring present pawl 96 and isitself carried by the lower end of link 87. A spring 97 vholds theseparts normally in the position of Fig. 5, where a. shield member 98holds the pawl outwardly. When the link 87 is raised, `as hereinbeforedescribed, the pawl 96 engages a ratchet segment 99 on a member 100which is fastened toshaft 92, and thus partially rotates the latteragainst the tension of the spring 93.

Engagement of the dog 82 with the arm 84 is adapted to move the pawl 96just far enough to advance the segment 99 through the distance of onetooth. yThe latter is held in the advanced' position by a hold pawl 101carried by a lever 102 which is pivoted at 103 and has' a spring 104attached to it to hold the pawl 101 in engagement with the teeth ofsegment 99. The link 89 is attached to one end of lever 102, anddepression of the link is adapted to raise pawl'101, as will readily beseen from'Fig. 5. In this connection it must -be noted that the finaltooth of segment 99 is higher than the rest, 'and depression of link 89in response to engagement of dog 83 with arm 88 does not raise 'pawl 101beyond the level of this last tooth.

The result is, that the rimary engagement of do 83 with arm 88 )ustdescribed, when the t'a le 1 moves to carry the grinding wheel '5 intoanew workpiece, leaves the parts as it finds them, in the position shownin Fig. 5. Immediately thereafter, however, by the engagement of dog 82with arm 84, the member 100 is moved through an angular distance of onetooth of the segment 99 and held there.

Referring now to Fig. 7, an insulating collar 105 is carried by theshaft 92. To the collar is fastened a metal finger 106. This finger '106is adapted to connect any one of the terminals 56, 57 and 58 with theplate 51.

When the table 1 has moved from the posi tion of Fig.- 1 to carry thewheel5 into a fresh workpiece, the finger 106, by the single actuationof the pawl 96 just described, has moved to connectterminal 56 withplate 51. Referring now to the wiring diagram of Fig. 4, it will be seenthat the electromagnet 47 will be energized as soon as the terminals 35land 39 come together. This causes the amplified movement of the table1, which has been described, and in consequence the dog 82 rocks the arm84 twice, once. as the t-able moves outwardly, and again as it movesinwardly..

more stages bringing it to rest in contact with terminal 57, where thetable will undergo another ampliiied movement when, and only whencontact is made between the terminals 36 and 40 in box 22. From theforegoing,

'enough caliper controlled contacts in the box 22 and enough progressiveswitch controlled contacts in t e casing 91.

Returning, however, to the specific embodiment of the invention shown inthe drawings the second amplified movement of the" table 1 moves thefinger 106 into contact with lterminal'58 (it being all the time incontact with plate. 51) where the same circuit is ready for energizationupon the making of contact at 37-41. This brin about a third amplifiedmovement and as t e table passes outwardly, the finger 106 is moved intothe @ted line position of Fig. 4; subsequent movements of pawl 96thereafter avail nothing since it has reached the right hand limit ofteeth in segment 99. Magnet 47 cannot be furtherenergized, and thegrinding wheel 5 proceeds to take the final and iinishing cuts on theworkpiece, and when the latter has reached the predetermined size,terminal 3'4 on lever 24 reaches terminal 38, which completes ja circuitthrough magnet 48 (entirely unconnect` ed with switch 52) thus raisingthe lever arm 79, whereupon the table 1 runs out to the posi-v tion ofFig. 1. This lfinal withdrawal carries the dog 83 past thearm 88, thusraising pawl-101 and returning all the elements attached to shaft 92 tothe` original position.

. This return movement occurs 1n res onse to the reaction of spring 93,since paw 96 except se ent 99 by the shield pin 98.

lferring nowto Figs. 1, 9, 11 and 123, the dressing diamonds, and theiraccompanying mechanismv are herein shown as mounted on the rear of themachine frame. designated by the numerals 107 and 108, respectively,land are carried by screw plugs 109 and 110 which fit in forwardlyextending ortions of oscillating memberslll and 112.

he latter'are rotatably mounted by means of bearings 113 and 114 on astand 115 which is adjustably attached to a base 116, as by means ofbolts 117-117 and a slot 118. In this manner coarse adjustments in theposi tion of the diamonds can be readily made, the individual and fineadjustments bein made by turning the screw plugs 109 an 110, bindingscrews 119 and 120 being provided to lock the plugs in any positron ofadjustment. The base' 116 is itself adjustably A attached to the machineframe by'bolts 121- 121 and a slot 122, said slot running in aldirectionat right angles to the aforesaid slot 118, whereby adjustments may bemade in two directions.v

The bearings' '113 land 114 are designed to eliminate all play, and oneconstruction which attains this end is shown in Fig.,9, but it is whenit is moved, is held away rom They ane,l

which diagrammatically shows the connec- Anot deemed necessary todescribe it in detail las this and many equivalent constructions forthis purpose are well known in the ma-' chine tool arts. In said Fig. 9,the dresser devices 107, 108 are both shown in the down or operativewhich, in t is machine, they never assume together, but the have been sodepicted to more clearly show t e relationship of these parts,

particularly how the diamonds 107 and 108 are brought to positionswhich, longitudinally considered, are close together, diamond 107 alsohaving a position slightly in advance of 108, laterally considered. Inthe said operative positions, lugs on the oscillating members 111 and112 strike lugs on the stand 115, or adjusting screws carried thereby,the construction being shown for the member 111 in Fig. 12, where 123 isthe lug on said member, 124 is the lug on the stand and 125 is theadjusting screw.

Referring now to'Figs. 12 and 13, the members 111 and 112 are moved ytobring the dressing diamonds from inoperative position to operativeposition and back a ain by levers 126 and 127, said levers being thpivotally mounted on a shaft 128 which is journalle'd in the base 116.The upper ends of levers 126 and 127 are connected to link rods 129 and130, the latter in turn being pivotally connected at 131 and 132 to themembers 111 and 112. Suitable adjustment de.

vices are provided at 133 and 134 and springs 135 take up any slack tothe parts. The levers 126 and 127 are moved to bring the diamonds downyby hydraulic means, and they are moved back again by mechanical means.In 'order to understand this'action and also the manner in which themachine automatically `shifts from the one dresser mechanism to theositions, this being a position,

lill) other, the fluid pressure control will now be explained, referencebeing first had to Fig. 8,

tions Any suitable pump 136 is provided to supply pressure fluld,desirably oil, to the dress-4 137. The discharge end of the pump 1s infdicated at 138 and it has been found desirable to connect a relief valve139 of any usual sort The at this point, the discharge of said reliefvalve leading by piping 139* to the sup ly source. Line fp1 ing 140connects to the dischar end -o t e pump, and connected to said inepiping is'a branch 141 which leads to the reversing valve and pressureuid cylinder that mctuates table 1. As aforesaid, such reversing valveis not shown herein, as

it forms no part of* our invention, lbut Fig. `8

shows the relationship between such and the hydraulic means toselectively move the different dressers, since a common source of fluidunder pressure suffices to actuate both the table 1 and the dressers. Inthe branch piping 141 is a slow-down or table speed reducing valve 142,which is shown in section in Fig. 8, and the operation of which will bedescribed hereinafter.

- The supply line 1.40 leads to an entrance port 143 of a valve which isgenerally designated by the numeral 144, and which is shown in truehorizontal section Fi 8. It is shown in vertical section in 1Fig. Avalve member 145 is adapted, in one posit-ion, to connect the port 143with a port 146 which leads the pressure fluid to the diamond movingmechanisms. In the other, or inoperative position, which is illustratedby Figs.`7 and 8, the port 143 is entirely closed, the port 146 beingconnected to an exhaust port 147 which communicates by piping 147 B withthe source of fluid supply. The valve member 145 is moved to theoperative position whenever the electromagnet 47 is energized, and tothis end a depending arm 148 is attached to the hub portion 149 whichholds the armature 73 and lever arm 74, these parts, of course, beingconveniently made in a single piece. The manner in which magnet 47 issuccessively energized to bringabout the several dressing operations hasbeen already described. Each separate energization thereof attracts thearmature7 3, and by means of the arm 148 and a` suitable connection 150,draws the valve member 145 to the operative osition. The amplifiedmovement of the ta le 1 is made use of to returrrthe parts to theoriginal position in the following manner. A cam portion 151, Fig. 1, iscarried either by the block 59, the block 61, or some member v amplifiedressing stroke,

the parts 73, 74 and 148 in raised, and therefore 4 a attached to eitherof these. shown herein, this cam of the latch lever 64. t all events itis in the path of the roller 75 on arm 74, and is so located that whenthe table 1 has reached approximatel the extreme outer limit of its saidcamI portion 151 engages the roller 75 and forcibly turns a clockwisedirection to their original position. It will be remembered that priorto such return movement, the said roller 75 was in engagement .with thelatch lever 64, the latter being stop 152 is provided to back up saidlatch lever 64 when the cam pox-'tion 151 comes into action. Thispositive means of returning the valve 145 to the position of Fig. 8 ishighly desirable, because, as will be hereinafter described, the dressermoving devices are mechanically reposi-l tioned by the return movementof table 1 after its amplified Withdrawal, yand such repositioningshould not take place until the ortion forms a part `outwardly a pin 162on As actually 94 pressure moving of fluid pressure.

The port 146 is connected, by means of piping 153, to the entrance port154 of a two- Way or selective valve 155. The position of the movable.member-156 of this valve determines which of the several dresser movingmechanisms will be operated. As is the case with valve 144, this valve155 is shown in vertical section in Fig. 7 and horizontal section inFig. 8.4 However, Fig. 7 shows it in one position, While Fig. 8 shows itin the other extreme position. In the position of Fig. 7 the entranceport 154 is connected to a port 157 which leads the pressure fluid bymeans of piping 158 and 159 to a cylinder 160, (see also Fig. 13) inwhich is a piston 161. This piston-161 is shown as having been moved tooperative position in Figs. 8 and 13 g-when fluid under pressure isforcedinto cylinder 160, the valve member 156 being in the position ofFig. possition shown'in these cylinders have been relieved figures, thuspushing lever 1,26, which action lowers the diamond 107. In similarfashion, when the valve member 156 is in the 7, said piston is moved tothe position of Fig. 8,.tl1e fl uid under pressure entering valve tranceport154,leaves itby distributing port 163, thence by piping 164 and 165to the other cylinder 166, moving a piston 167 outwardly,

(which is shown in its initial position in Fi s. 8 and 13), thus movinga pin 168 attac ed to lever 127. This, of course, lowers the diamond108.

Referring to Figs. 6 and 7, the member 94, already referred toasfastened tothe shaft 92, is a cam member, the contour of which can beplainly seen in Fig. 7. Pivotally mounted at 169 is a lever 170, whichprpvides a roller 1,71- engaging the periphery of .said cam member Acoil spring 170a surrounds the hub of lever 17 0, one end of the springbeing looped around the lever and the other end being atthus the lever170 is 7 shown by Fig. 7, the valve member 156 'is in its left handposition, ready to connect the pressure fluid line 140 to the diamondoperating cylinder 160 by Way of port 157. When the metal finger 106 hasmoved cam member 94 has moved the lever 170 to shift the valve member156 to the position shown in Fig. 8, in which position, in theparticular arrangement of shown by the drawings, it is held after theAfirst dressing has been completed and until the workpiece beingoperated upon is finished. As previously described, this valve acts Theupper to the position where 1t connects the terminals 51 and 57, the'155 by way of the single enthe invention simply as a distributing`valve, while the actual functioning of the particulardiamond which is to'be operated is controlled by the Y operation of upper valve member 145.

As aforesaid, the dresser points are raised, and the pitsons 161 and 167are replaced by mechanical means. Referring to Figs. 11, 12, 13 and 14,a cam member 173 is suitably fastened to the table 1 at the rearthereof, as

l by bolts 174, 174, provision beingmade for to lrollers 181 and182,-the latter being carried, respectively, by forward extensions 183and 184 of levers-126 and 127. The roller 181 is shown in the u pposition in this figure, which corresponds to Figs;` 12 and 13. Movementof the table 1 to carry the grinding'wheel 5 back into the work piece 6,forces the roller 181 downwardly, thus rocking the lever 126 in .acounterclockwise direction (Fig. 12). This action restores the diamond107 to the inoperative position, and forces back the piston 161. Fluidis consequently ejected from the cylinder 160. The valve member 145having already been repositioned in the manner described, the is openedup, but atthis stage in theoperation of the machine, the valve member156 has just been sliiftedto make ready for the operation of the otherdiamond, so exhaust port 147 is cut off from cylinder 160. See Fig. 8.Consequently auxiliary exhaust ports 185 an'd 186 are provided in thevalve 155, said ports leading to a chamber 187 (see Fig. 7) whichexhausts by piping 188 to the main fluid supply. Thus the fluid fromthecylinder 160 exhausts by way of port 185.

It will be readily understood that in exactly similar fashion, thediamond 108 and pistonl 167 are mechanically repositioned by contact ofsurface 180 with roller 182,-when this hap ns, either subsequent to 'thefirst or secon dressing of the grinding wheel 5 by the diamond 108, thevalve members 145 and 156 are in the position shown in Fig. 8, theformer having been moved by subsequent electrical contacts in thecontrol mechanism since the stage at which the cylinder 160 wasexhausted, but the latter having remained stationary, and consequentlythe fluid from cylinder 166 exhausts, by the normal exhaust port 147 invalve 144. Auxiliary port 186 serves no direct function in'v` thepresent arrangement of the invention, but acts as a safety port, andallows the dresser moving operations to be reversed, as by simplycrossing pipes 4158 and 164.

Still referring to Fig. 8, the table speed reducing valve a slow downvalve 142, hereinbefore referredto, comprises a rotatable valvev member189 having a hole 190 therethrough. Said valve member is actuated by ashaft 189. Turning of the valve member offsets said hole. 190 toentrance and exit ports 191 and 192, and thus restricts the passage ofthe pressure fiuidto the table operating cylinder, not shown. To theshaft`189 of member 189 is fastened a member 193 asshown in Fig. 12,having-a long arm 194 and a short arm 195. Connected to the said longarm 194 is a link 196, which also connects to a depending lever arm 197keyed to shaft 128. 'lhus it will be seen that the valve 142 iscontrolled from shaft 128, the angular position ofthe latter f I beingin turn controlled from the levers 126 and 127, as follows. y

Refering to Fig. 10, a collar 198 is also splined to said shaft 128.This collar provides an upwardly extending pair of lugs 199 and 200.Each diamond operating lever 126 and 127 has a pair of spaced lugs; 201and 202 203 and 204 in the in the case of lever 126; case oflever 127.Adjustment screws 201, 202, 203 andv 204", respectively, are carried bysaid lugs. Collar 198 is controlled in longitudinal position by a pin205 attached to an arm 206, short shaft 207 which extends upwardly froma casing 208., Inthe inside of said casing is a flap valve member 209,which is likewise atnormal exhaust port 147 tached to said short shaft207.

Ports 210 and 211 in this casing connect to4 and another piping 158 and164, respectively, pair of ports 212 and 213 (in the top part of thecasing) connect to piping 159 and 165. Vhen fluid flows through piping158, it enters lthe casing 208 at port 210 and forces the the latterbeing fastened to a ics flap valve 209 to the position shown in Fig. y

10, thusallowing'luid to exit by port 212, thence through piping 159 tocylinder 160. The fla valve is likewise held in this position when t efluid exhausts by way of piping 159. When fluid comes in by way ofpiping 164, the valve member 209 is forced to an op osite position andlikewise is held there by tllie exhaust of such seen that the upperports 212 and 213 are elongated in shape so that. neither of them canever be entirely closed. This prevents locking of fluid in the diamondoperating cylinders, which mi ht otherwise occur in case flap valve 209sliould be manually moved to the wrong position. The arm 206 is, ofcourse, moved in accordance with the 'position of flap valve 209, and sothe collar 198 is also moved, and the lugs 199 and 200 fit,respectively, between screws 201l and 202", or 203", 204, as the casemay be. So any desired control can be automatically exercised on thevalve 142, since turning of shaft 128 is fluid. From Fig. 10 it will bebound to result when one of the above screws strikes a correspondinglug, said screws being` carried, as stated, by the lever arms 126 and127, and shaft 1-28 being operatively connected to the valve member,through the arm 197. l

It will readily be seen that any range of speed of the table 1 can beworked out for the different dressing strokes, the intermediate cuttingstrokes on the workpiece between said dressing strokes and the final andfinishing cutting strokes on the workpiece, merely by properly adjustingthe s rews 2011, 202, 203a and 204-. AThe possib e combinationsl are toonumerous to. recite suifice it to say that adjustments of screws 202*land 201g' will control, respectively, the speed to which the tablereciprocation Ais reduced during the wheel dressing by the d'amond 107,and the speed to which the tab e returns during the workingreciprocations immediately following this dressing. Likewise, theadjustments of screws 204a the corresponding speeds during and after thedressing operation by the .diamond 108.

However, it is desirable that after a given workpiece is finished, thevalve member 189 should be returned to the original position of freeiiow of the pressure fluid, irrespective of the setting of theadjustment screws. So, re-

' ferring to Figs. 12 and 14, a third cam surface chine with the table 1in 214 is provided on bar 17 3, said surface facing inthe oppositedirection from the other surfaces 179 and 180. In the path of surface214 isa roller215 on aA rod 216 which passes down through a bearing inthe machine frame. A link 217 is connected to the bottom of this rod,and the other end of thevlink 217 connects to the short arm 195 alreadyreferred to. When the table withdraws to the position of .Fig 1, after aWorkpieceis finished, the surface 214 strikes and depresses the roller215, moving downwardly the rod 2,16 and link 217, and thus thevalvemember 189 is restored to the osition of free flow.

Tige operation of the machine has been set forth with the description ofparts, but briefly recapitiilating, the operator finds the lmatheposition of Fig. 1. Assuming that all necessary adjustments have beenmade, he lplaces an unground workpiece in the chuck 6, sets the latterin rotation, and likewise causes the spindle 10 to be rapidly rotated.By movement of the'lever 90, the table is startedto carry the grindingwheel 5 toward the workpiece 6,the reversing member 9 automaticallyassuming its position between dogs 7 and 8. The caliper control box 22swings inwardly, car ing the point 16 into contact with the internasurface of the workpiece. The preliminary cuts are now taken on theworkpiece, but before the wheel 5 has a. chance to get dull, theterminal 35 reaches the terminal 39 and the table moves outwardly in anamplified stroke, carrying and 203a control, respectively,

the Wheel 5 past the diamond 107, which has been lowered as set forth.The cutting operation is resumed, at reduced speed of table traverse, ifdesired, in accordance with the automatic setting of the valve 142.Later in the operation on this workpiece, and desirably after asubstantial advance has been given to the feed screw shaft 11, the tableundergoes a second amplification, and the wheel is dressed aga-in, thistime by the diamond 108. Thereafter the cutting operation is againresumed, but only for a few strokes, since the wheel is again to bedressed by the saine ldiainond 108 when contacts 37 and 4l in the box 22come together. This double dressing from a single diamond which reachesa given operative position is possible because a slight spring alwaysexists in the spindle 10 subsequent to a comparatively great number ofworkpiece reducing strokes. ISubsequent to a second dressing of thewheel 5 by a given diamond, however, practically no spring is present inthe spindle 10, and the workpiece is finished, desirably at reducedspeed of table traverse, whereupon the contacts 34 and 38 come togetherand the table again runs out to the position of Fig. 1. i

Thus the grin-ding wheel 5 is kept sharp and free cutting during theentire operation of reducing the workpiece, and therefore extremely hardworkpieces can be accurately ground. It is obvious that by simplysubstituting a different cam 94, the wheel A5 can be dressed twice onthe first diamond 107, or indeed it could be dressed all three times onany given diamond. Also, by merely prol viding more' contacts in theprogressive switch mechanism and in the box 22, any number of dressingoperations could be brought about. Many other changes in thelarrangement and form of the invention can be made, the scope of theinvention being set forth in the following claims.

We claim:

1. In a grinding machine, a plurality of wheeldressingdevic-es,'hydraulic means automatically brought into action to severallymove said devices into operative posit-ion at different stages in thereduction of a workpiece, and mechanical means also automaticallybrought into action to reposition said devices.

2. In a Grinding machine, a plurality of hydraulically operated dressermoving mechanisms, a selective valve device to determine which of saidmechanisms will be operated, and a progressive mechanism toactuatevsa'id selective valve. v

3. 'In a grinding machine, me r bringing a dressing point to a givenoperative position, means for bringing a secoiidl'fdressing point toanother operative position, and selective means automatically bringingsaid first with 'a plurality of movable dresser devices, separate meansto actuate said dresser devices, a reciprocating table and a speedcontrol for said'table, of means actuated severally by the separatemeans to actuate said drelsser devices, for operating said speed contro5. In a inding machine, areciprocatory table, a p urality of dressers,and separate means torontrol the speed of said table responsiveseverally to move-ment of said dressers. l d

6. In a grinding machine, a plurality of dressing devices, hydraulicmeans for severally actuating said devices to move them tooperativeposltion'., and mechanical means to replace them in inoperativeposition.

7. In a grinding machine, a pair of hydraulically'operated dressers, aAreciprocatory y su table, a control device to govern the speed of saidtable, and means for shifting said control device from one to the otherof said dressers, said control being shifted by the flow of pressurefluid to operate a given dresser. v

8. In a grinding machine, a pair of movable dresser devices, actuatingmeans for said dressers, a work-sizing mechanism, andselective meansunder the control of said wor'k` sizing mechanism to cause one orthe'other of said-dressers to be actuated.

9. In a grinding machine, a grinding wheel, means for feeding said wheelin cutting relation to a workpiece, means for dress said wheel byadressing device located ntially in the plane of the wheel axiswhichcontains the cutting line of the wheel,

further means for dressin said wheel by aV dressi device located sutantially in, the same p ane but at'adierent position in the`progressive control line of feed, a Work sizing mechanism, and amechanism, the latter, in response to movement controlled by the worksizing mechanism determining which of said dressing means shall bebrought into operation.

10. In a grinding machine, a grinding -Wheel, means for feeding saidWheel in cutting relation to a workpiece, means for dressing said wheelby a dressin device located substantially in the plane o the Wheel axiswhich contains the cutting line of the wheel, further means for dressingsaid wheel by a dressinor device located substantially in the same panebut at a different position in the line of feed, a progressive controlmechanism which determines which of said dressin means shall be broughtinto operation, an means for moving said progressive control mechanismto a different stage for each dressing. Y

11. In-a grinding machine, a plurality of dresser moving mechanisms,selective means to determine which of said 'mechanisms will be operated,and a progressive mechanism to actuate said selective means.

12. `In a grinding machine, a pair of dress'- ing devices, separatemeans to operate said.

dressers, a reciproc'atory table, a control del vice toy govern thespeed of. said table, and means for shifting said control device fromone to the other of said dressers, said control being shiftedautomatically to the dresser operating-means that is' made active at theinitiation of its action.

'Dated this 21st day of April, 1926.

RICHARD A. HEALD. 'CARLE J. HIGHBERG. EDWARD M. TAYLOR.

